Last week, Jack sent me this link about the preventive health and aspirin [it is called ASA in Canada unless it is produced by Bayer]. This article seems to be a thorough summary of the literature.
I have been taking low-dose aspirin daily for about a decade because both my parents died of heart disease, but I had no idea that low-dose aspirin might also play a role in reducing the risk of some cancers.
From the conclusion,
The benefits of aspirin in secondary prevention of cardiovascular events are well established, with significant reductions reported in the risk of MI, stroke, and other serious vascular events in men and women.... Aspirin has been shown to reduce the overall risk for total cardiovascular events and nonfatal MI, but the evidence is not consistent regarding the risk for CHD, stroke, cardiovascular mortality, and all-cause mortality. There appear to be differences in the benefits for men and women; in men, it is associated with a reduction in MI and cardiovascular events, but not stroke and cardiovascular mortality. In women, aspirin treatment is associated with a reduction in the risk of ischemic stroke but not MI or cardiovascular mortality. Although the use of prophylactic low-dose aspirin for primary prevention of CVD is recommended in several clinical guidelines, there remains intense debate among experts about its value in low-risk populations due to the increased risk of GI and intracranial bleeding. Guidelines stress the importance of assessing the risks and benefits on an individual patient basis, and some experts argue that general guidelines are not justified.[10] ...
There is a growing body of evidence for the benefits of aspirin in reducing the risk of cancer, most notably colorectal cancer, with the effect becoming clinically apparent after approximately 5 years. Several potentially relevant clinical trials are due to be completed between now and 2019, and these may clarify the extent of the benefits of aspirin in reducing the risk of cancer incidence and mortality.[4] The chemopreventive benefits of aspirin appear to be long-term and the bleeding risk from aspirin use is short-term and appears to diminish over time. For most individuals the risk-benefit assessment appears to be weighted in favor of the anticancer benefits from aspirin. Although current data do not allow a definitive conclusion to be made about routine use of aspirin for cancer prevention, ongoing study findings make it more likely that recommendations for aspirin use in primary prevention will be broadened in the future so that the benefits of aspirin use are not restricted to CVD alone.[8]
I.e., if you haven't had a heart attack, low-dose aspirin might help reduce the odds of having one, but the evidence is not overwhelming. Also it might help reduce the risk of developing colorectal cancer.
JR sent this link, which seems slightly more skeptical:
Aspirin works to reduce events among patients who have a higher likelihood of having an event, and there remains an argument for aspirin in patients who are at exceptionally high risk but who have not yet had a heart attack or a stroke. This has led to some controversy in this issue, and varying interpretations. However the potential for aspirin to be beneficial in this group remains largely speculative, and the source article cited above examined even the highest risk patients who had not had a heart attack or stroke in trials, and there was no demonstrable benefit to aspirin even for these patients (though this subgroup was small in these trials).
And he also sent this link, which seems quite skeptical concerning the use of low-dose aspirin for primary care (i.e. as a preventive treatment for people who have not had previous incidents).
I carry uncoated aspirin with me all the time. One of the best things to do if you feel you might be having a heart attack is to take a couple of uncoated aspirins right away.